NASA Hubble Space Telescope Daily Report #5072
HUBBLE SPACE TELESCOPE DAILY REPORT #5072
Continuing to Collect World Class Science
PERIOD COVERED: 5am April 9 – 5am April 12, 2010 (DOY 099/09:00z-102/09:00z)
OBSERVATIONS SCHEDULED
ACS/WFC 11995
CCD Daily Monitor (Part 2)
This program comprises basic tests for measuring the read noise and dark current of the ACS WFC and for tracking the growth of hot pixels. The recorded frames are used to create bias and dark reference images for science data reduction and calibration. This program will be executed four days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To facilitate scheduling, this program is split into three proposals. This proposal covers 320 orbits (20 weeks) from 1 February 2010 to 20 June 2010.
WFC3/IR/S/C 11929
IR Dark Current Monitor
Analyses of ground test data showed that dark current signals are more reliably removed from science data using darks taken with the same exposure sequences as the science data, than with a single dark current image scaled by desired exposure time. Therefore, dark current images must be collected using all sample sequences that will be used in science observations. These observations will be used to monitor changes in the dark current of the WFC3-IR channel on a day-to-day basis, and to build calibration dark current ramps for each of the sample sequences to be used by Gos in Cycle 17. For each sample sequence/array size combination, a median ramp will be created and delivered to the calibration database system (CDBS).
WFC3/UVIS 11908
Cycle 17: UVIS Bowtie Monitor
Ground testing revealed an intermittent hysteresis type effect in the UVIS detector (both CCDs) at the level of ~1%, lasting hours to days. Initially found via an unexpected bowtie-shaped feature in flatfield ratios, subsequent lab tests on similar e2v devices have since shown that it is also present as simply an overall offset across the entire CCD, i.e., a QE offset without any discernable pattern. These lab tests have further revealed that overexposing the detector to count levels several times full well fills the traps and effectively neutralizes the bowtie. Each visit in this proposal acquires a set of three 3×3 binned internal flatfields: the first unsaturated image will be used to detect any bowtie, the second, highly exposed image will neutralize the bowtie if it is present, and the final image will allow for verification that the bowtie is gone.
WFC3/UVIS 11905
WFC3 UVIS CCD Daily Monitor
The behavior of the WFC3 UVIS CCD will be monitored daily with a set of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K subarray biases are acquired at less frequent intervals throughout the cycle to support subarray science observations. The internals from this proposal, along with those from the anneal procedure (Proposal 11909), will be used to generate the necessary superbias and superdark reference files for the calibration pipeline (CDBS).
STIS/MA1/MA2 11857
STIS Cycle 17 MAMA Dark Monitor
This proposal monitors the behavior of the dark current in each of the MAMA detectors.
The basic monitor takes two 1380s ACCUM darks each week with each detector. However, starting Oct 5, pairs are only included for weeks that the LRP has external MAMA observations planned. The weekly pairs of exposures for each detector are linked so that they are taken at opposite ends of the same SAA free interval. This pairing of exposures will make it easier to separate long and short term temporal variability from temperature dependent changes.
For both detectors, additional blocks of exposures are taken once every six months. These are groups of five 1314s FUV-MAMA Time-Tag darks or five 3x315s NUV ACCUM darks distributed over a single SAA-free interval. This will give more information on the brightness of the FUV MAMA dark current as a function of the amount of time that the HV has been on, and for the NUV MAMA will give a better measure of the short term temperature dependence.
STIS/CC 11847
CCD Bias Monitor-Part 2
Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1, and 1×1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns.
STIS/CC 11845
CCD Dark Monitor Part 2
Monitor the darks for the STIS CCD.
COS/NUV/FUV 11728
The Impact of Starbursts on the Gaseous Halos of Galaxies
Perhaps the most important (yet uncertain) aspects of galaxy evolution are the processes by which galaxies accrete gas and by which the resulting star formation and black hole growth affects this accreting gas. It is believed that both the form of the accretion and the nature of the feedback change as a function of the galaxy mass. At low mass the gas comes in cold and the feedback is provided by massive stars. At high mass, the gas comes in hot, and the feedback is from an AGN. The changeover occurs near the mass where the galaxy population transitions from star-forming galaxies to red and dead ones. The population of red and dead galaxies is building with cosmic time, and it is believed that feedback plays an important role in this process: shutting down star formation by heating and/or expelling the reservoir of cold halo gas. To investigate these ideas, we propose to use COS far-UV spectra of background QSOs to measure the properties of the halo gas in a sample of galaxies near the transition mass that have undergone starbursts within the past 100 Myr to 1 Gyr. The galactic wind associated with the starburst is predicted to have affected the properties of the gaseous halo. To test this, we will compare the properties of the halos of the post-starburst galaxies to those of a control sample of galaxies matched in mass and QSO impact parameter. Do the halos of the post-starburst galaxies show a higher incidence rate of Ly-Alpha and metal absorption-lines? Are the kinematics of the halo gas more disturbed in the post-starbursts? Has the wind affected the ionization state and/or the metallicity of the halo? These data will provide fresh new insights into the role of feedback from massive stars on the evolution of galaxies, and may also offer clues about the properties of the QSO metal absorption-line systems at high-redshift .
ACS/WFC 11715
The Luminous Galactic Cepheid RS Puppis: A Geometric Distance from its Nested Light Echoes
RS Puppis is one of the most luminous Cepheids in the Milky Way (P = 41.4 days) and an analog of the bright Cepheids used to measure extragalactic distances. An accurate distance would help anchor the zero-point of the bright end of the period-luminosity relation, but at a distance of about 2 kpc it is too far away for a trigonometric parallax with existing instrumentation.
RS Pup is unique in being surrounded by a reflection nebula, whose brightness varies as pulses of light from the Cepheid propagate outwards. Members of our team have used ground-based imaging of the nebula to derive phase lags in the light variations of individual features in the nebula, and have inferred a seemingly very precise geometric distance to the star. However, there is an unavoidable ambiguity involving the cycle counts, which was resolved by assuming that the features lie in the plane of the sky. If this assumption is incorrect, a large systematic error would be introduced into the distance measurement.
We show that polarimetric imaging using the high spatial resolution of ACS/WFC and its ability to image close to the star can resolve this ambiguity and yield a reliable geometric distance to RS Pup. We will also obtain a wide-field multicolor image of the nebula, in order to study its morphology and the mass-loss history of the Cepheid.
WFC3/UV/IR 11709
Stretching the Diversity of Cosmic Explosions: The Supernovae of Gamma-ray Bursts
While the association between gamma-ray bursts (GRBs) and massive stars is robust, there is a large diversity of properties among supernovae (SNe) associated with GRBs. The converse is also true: Several recent events show that there is a large brightness range among high energy transients associated with SNe. As part of a comprehensive program, we propose to use HST in order to search for and characterize the SNe associated with GRB.
HST offers the means to cleanly separate the light curve of the GRB afterglow from the supernova, and to remove the contamination from the host galaxy, opening a clear path to the fundamental parameters of the SN, and thence to the progenitor. From these observations, we will determine the absolute magnitude at maximum, the shape of the spectral energy distribution, and any change over time of the energy distribution. We will also measure the rate of decay of the exponential tail.
Merged with the ground-based data that we will obtain for each event, we will be able to compare our data set to models and constrain the energy of the explosion, the mass of the ejecta and the mass of Nickel synthesized during the explosion. These results will shed light on the apparent variety of supernovae associated with gamma-ray bursts and X-ray flashes, and on the relation between these SNe and other, more common, types of core-collapse explosions.
STIS/CCD 11703
The Nature of the Black Hole in a NGC 4472 Globular Cluster and the Origin of Its Broad [OIII] Emission
We propose to use STIS to obtain optical spectroscopy at high spatial resolution of the black hole-hosting globular cluster RZ2109 in the Virgo elliptical NGC 4472. This is motivated by our very recent discovery broad [OIII] 4959, 5007 emission with a width of several thousand km/s in this globular cluster. The STIS spectroscopy will enable us to determine if the very broad [OIII] emission is due to material driven at high velocity from the central accreting black hole across the globular cluster, or if the velocity widths are due to gravitational motions very close to the central black hole. In the former case, the [OIII] emission should extend over a few-tenths of an arcsecond and be spatially resolved by HST and STIS, while in the latter case, the emission lines will be unresolved. Distinguishing between these two possibilities will allow us to – 1) determine whether the black hole is of intermediate mass or a stellar mass, and thereby whether the black hole mass – sigma relation extends to globular cluster masses, 2) test models of black hole formation and evolution in dense stellar systems, and 3) address the nature of accretion in the high luminosity black-hole X-ray source, and constrain the feedback processes from luminous black holes into their surrounding medium in dense stellar systems.
COS/FUV 11699
On the Evolutionary Status of Extremely Hot Helium Stars – are the O(He) Stars Successors of the R CrB Stars?
We propose UV spectroscopy of the four unique post-AGB stars of spectral type O(He) in order to understand the origin of their peculiar surface abundances. These stars are the only known amongst the hottest post-AGB stars (effective temperatures > 100, 000 K) whose atmospheres are composed of almost pure helium. This chemistry markedly differs from that of the hydrogen-deficient post-AGB evolutionary sequence with objects which have carbon dominated atmospheres (PG1159 stars and Wolf-Rayet central stars).
While PG1159 and Wolf-Rayet stars are the result of a late helium-shell flash, this scenario cannot explain the O(He) stars. Instead, they are possibly double-degenerate mergers. We speculate that the four O(He) stars represent evolved RCrB stars, which also have helium-dominated atmospheres. We aim to determine the C, N, O, and Si abundances precisely, in order to proof this evolutionary link.
WFC3/IR 11696
Infrared Survey of Star Formation Across Cosmic Time
We propose to use the unique power of WFC3 slitless spectroscopy to measure the evolution of cosmic star formation from the end of the reionization epoch at z>6 to the close of the galaxy- building era at z~0.3.Pure parallel observations with the grisms have proven to be efficient for identifying line emission from galaxies across a broad range of redshifts. The G102 grism on WFC3 was designed to extend this capability to search for Ly-alpha emission from the first galaxies. Using up to 250 orbits of pure parallel WFC3 spectroscopy, we will observe about 40 deep (4-5 orbit) fields with the combination of G102 and G141, and about 20 shallow (2-3 orbit) fields with G141 alone.
Our primary science goals at the highest redshifts are: (1) Detect Lya in ~100 galaxies with z>5.6 and measure the evolution of the Lya luminosity function, independent of of cosmic variance; 2) Determine the connection between emission line selected and continuum-break selected galaxies at these high redshifts, and 3) Search for the proposed signature of neutral hydrogen absorption at re-ionization. At intermediate redshifts we will (4) Detect more than 1000 galaxies in Halpha at 0.5< z<1.8 to measure the evolution of the extinction-corrected star formation density across the peak epoch of star formation. This is over an order-of-magnitude improvement in the current statistics, from the NICMOS Parallel grism survey. (5) Trace ``cosmic downsizing" from 0.5< z<2.2; and (6) Estimate the evolution in reddening and metallicty in star- forming galaxies and measure the evolution of the Seyfert population. For hundreds of spectra we will be able to measure one or even two line pair ratios -- in particular, the Balmer decrement and [OII]/[OIII] are sensitive to gas reddening and metallicity. As a bonus, the G102 grism offers the possibility of detecting Lya emission at z=7-8.8. To identify single-line Lya emitters, we will exploit the wide 0.8–1.9um wavelength coverage of the combined G102+G141 spectra. All [OII] and [OIII] interlopers detected in G102 will be reliably separated from true LAEs by the detection of at least one strong line in the G141 spectrum, without the need for any ancillary data. We waive all proprietary rights to our data and will make high-level data products available through the ST/ECF. COS/FUV 11686 The Cosmological Impact of AGN Outflows: Measuring Absolute Abundances and Kinetic Luminosities AGN outflows are increasingly invoked as a major contributor to the formation and evolution of supermassive black holes, their host galaxies, the surrounding IGM, and cluster cooling flows. Our HST/COS proposal will determine reliable absolute chemical abundances in six AGN outflows, which influences several of the processes mentioned above. To date there is only one such determination, done by our team on Mrk 279 using 16 HST/STIS orbits and 100 ksec of FUSE time. The advent of COS and its high sensitivity allows us to choose among fainter objects at redshifts high enough to preclude the need for FUSE. This will allow us to determine the absolute abundances for six AGN (all fainter than Mrk 279) using only 40 HST COS orbits. This will put abundances studies in AGN on a firm footing, an elusive goal for the past four decades. In addition, prior FUSE observations of four of these targets indicate that it is probable that the COS observations will detect troughs from excited levels of C III. These will allow us to measure the distances of the outflows and thereby determine their kinetic luminosity, a major goal in AGN feedback research. 11686( 7) – 25-Sep-2009 13:44:14 – [ 2] We will use our state of the art column density extraction methods and velocity-dependent photoionization models to determine the abundances and kinetic luminosity. Previous AGN outflow projects suffered from the constraints of deciding what science we could do using ONE of the handful of bright targets that were observable. With COS we can choose the best sample for our experiment. As an added bonus, most of the spectral range of our targets has not been observed previously, greatly increasing the discovery phase space. WFC3/ACS/IR 11677 Is 47 Tuc Young? Measuring its White Dwarf Cooling Age and Completing a Hubble Legacy With this proposal we will firmly establish the age of 47 Tuc from its cooling white dwarfs. 47 Tuc is the nearest and least reddened of the metal-rich disk globular clusters. It is also the template used for studying the giant branches of nearby resolved galaxies. In addition, the age sensitive magnitude spread between the main sequence turnoff and horizontal branch is identical for 47 Tuc, two bulge globular clusters and the bulge field population. A precise relative age constraint for 47 Tuc, compared to the halo clusters M4 and NGC 6397, both of which we recently dated via white dwarf cooling, would therefore constrain when the bulge formed relative to the old halo globular clusters. Of particular interest is that with the higher quality ACS data on NGC 6397, we are now capable with the technique of white dwarf cooling of determining ages to an accuracy of +/-0.4 Gyrs at the 95% confidence level. Ages derived from the cluster turnoff are not currently capable of reaching this precision. The important role that 47 Tuc plays in galaxy formation studies, and as the metal-rich template for the globular clusters, makes the case for a white dwarf cooling age for this metal-rich cluster compelling. Several recent analyses have suggested that 47 Tuc is more than 2 Gyrs younger than the Galactic halo. Others have suggested an age similar to that of the most metal poor globular clusters. The current situation is clearly uncertain and obviously a new approach to age dating this important cluster is required. With the observations of 47 Tuc, this project will complete a legacy for HST. It will be the third globular cluster observed for white dwarf cooling; the three covering almost the full metallicity range of the cluster system. Unless JWST has its proposed bluer filters (700 and 900 nm) this science will not be possible perhaps for decades until a large optical telescope is again in space. Ages for globular clusters from the main sequence turnoff are less precise than those from white dwarf cooling making the science with the current proposal truly urgent. WFC3/UVIS/IR 11662 Improving the Radius-Luminosity Relationship for Broad-Lined AGNs with a New Reverberation Sample The radius-luminosity (R-L) relationship is currently the fundamental basis for all techniques used to estimate black hole masses in AGNs, in both the nearby and distant universe. However, the current R-L relationship is based on 34 objects that cover a limited range in black hole mass and luminosity. To improve our understanding of black hole growth and evolution, the R-L relationship must be extended to cover a broader range of black hole masses using the technique known as reverberation mapping. To this end, we have been awarded an unprecedented 64 nights on the Lick Observatory 3-m telescope between March 24 and May 31, 2008, to spectroscopically monitor 12 AGNs in order to measure their black hole masses. To properly determine the luminosities of these 12 AGNs, we must correct them for their host-galaxy starlight contributions using high-resolution images. Previous work by Bentz et al. (2006) has shown that the starlight correction to AGN luminosity measurements is an essential component to interpreting the R-L relationship. The correction will be substantial for each of the 12 sources we will monitor, as the AGNs are relatively faint and embedded in nearby, bright galaxies. Starlight corrections are not possible with ground-based images, as the PSF and bulge contributions become indistinguishable under typical seeing conditions, and adaptive optics are not yet operational in the spectral range where the corrections are needed. In addition, spectral decompositions are very model-dependent and are limited by the degree of accuracy to which we understand emission processes and stellar populations in galaxies. Without correcting for starlight, we will be unable to apply the results of our Spring 2008 campaign to the body of knowledge from previous reverberation mapping work. Therefore, we propose to obtain high resolution, high dynamic range images of the host galaxies of the 12 AGNs in our ground-based monitoring sample, as well as one white dwarf which will be used as a PSF model. WFC3/UVIS/IR 11644 A Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into the Formation of the Outer Solar System The eight planets overwhelmingly dominate the solar system by mass, but their small numbers, coupled with their stochastic pasts, make it impossible to construct a unique formation history from the dynamical or compositional characteristics of them alone. In contrast, the huge numbers of small bodies scattered throughout and even beyond the planets, while insignificant by mass, provide an almost unlimited number of probes of the statistical conditions, history, and interactions in the solar system. To date, attempts to understand the formation and evolution of the Kuiper Belt have largely been dynamical simulations where a hypothesized starting condition is evolved under the gravitational influence of the early giant planets and an attempt is made to reproduce the current observed populations. With little compositional information known for the real Kuiper Belt, the test particles in the simulation are free to have any formation location and history as long as they end at the correct point. Allowing compositional information to guide and constrain the formation, thermal, and collisional histories of these objects would add an entire new dimension to our understanding of the evolution of the outer solar system. While ground based compositional studies have hit their flux limits already with only a few objects sampled, we propose to exploit the new capabilities of WFC3 to perform the first ever large-scale dynamical-compositional study of Kuiper Belt Objects (KBOs) and their progeny to study the chemical, dynamical, and collisional history of the region of the giant planets. The sensitivity of the WFC3 observations will allow us to go up to two magnitudes deeper than our ground based studies, allowing us the capability of optimally selecting a target list for a large survey rather than simply taking the few objects that can be measured, as we have had to do to date. We have carefully constructed a sample of 120 objects which provides both overall breadth, for a general understanding of these objects, plus a large enough number of objects in the individual dynamical subclass to allow detailed comparison between and within these groups. These objects will likely define the core Kuiper Belt compositional sample for years to come. While we have many specific results anticipated to come from this survey, as with any project where the field is rich, our current knowledge level is low, and a new instrument suddenly appears which can exploit vastly larger segments of the population, the potential for discovery — both anticipated and not — is extraordinary. WFC3/UV 11635 In Search of SNIb/Ic Wolf-Rayet Progenitors and Comparison with Red Supergiants (SNII Progenitors) in the Giant ScI Spiral M101 We propose to test two of the clearest predictions of the theory of evolution of massive-star evolution: 1) The formation of Wolf-Rayet stars depends strongly on these stars’ metallicity (Z), with relatively fewer WR stars forming at lower Z, and 2) Wolf-Rayet stars die as Type Ib or Ic supernovae. To carry out these tests we propose a deep, narrowband imaging survey of the massive star populations in the ScI spiral galaxy M101. Just as important, we will test the hypothesis that Superclusters like 30 Doradus are always richly populated with WR stars, and by implication that these complexes are responsible for the spectral signatures of starburst galaxies. Our previous HST survey of the HII regions in the ScIII galaxy NGC 2403 suggested that the distribution of WR stars and RSG is a sensitive diagnostic of the recent star-forming history of these large complexes: young cores of O and WR stars are surrounded by older halos containing RSG. Theory predicts that this must change with metallicity; relatively fewer WR stars form at lower Z. A key goal of our proposal is to directly test this paradigm in a single galaxy, M101 being the ideal target. The abundance gradient across M101 (a factor of 20) suggests that relatively many more WR will be found in the inner parts of this galaxy than in the outer “suburbs”. Second, we note that WR stars are predicted to end their lives as core-collapse or pair-instability supernovae. The WR population in M101 may be abundant enough for one to erupt as a Type Ib or Ic supernova within a generation. The clear a priori identification of a WR progenitor would be a major legacy of HST. Third, we will also determine if “superclusters”, heavily populated by WR stars, are common in M101. It is widely claimed that such Superclusters produce the integrated spectral signatures of Starburst galaxies. We will be able to directly measure the numbers and emission-line luminosities of thousands of Wolf Rayet stars located in hundreds of M101 Superclusters, and correlate those numbers against the Supercluster sizes and luminosities. It is likely (but far from certain) that Supercluster sizes and emission-line luminosities are driven by their Wolf-Rayet star content. Our sample will be the largest and best-ever Supercluster/Wolf Rayet sample, an excellent local proxy for characterizing starburst galaxies’ Superclusters. COS/FUV 11625 Beyond the Classical Paradigm of Stellar Winds: Investigating Clumping, Rotation and the Weak Wind Problem in SMC O Stars SMC O stars provide an unrivaled opportunity to probe star formation, evolution, and the feedback of massive stars in an environment similar to the epoch of the peak in star formation history. Two recent breakthroughs in the study of hot, massive stars have important consequences for understanding the chemical enrichment and buildup of stellar mass in the Universe. The first is the realization that rotation plays a major role in influencing the evolution of massive stars and their feedback on the surrounding environment. The second is a drastic downward revision of the mass loss rates of massive stars coming from an improved description of their winds. STIS spectroscopy of SMC O stars combined with state-of-the-art NLTE analyses has shed new light on these two topics. A majority of SMC O stars reveal CNO- cycle processed material brought at their surface by rotational mixing. Secondly, the FUV wind lines of early O stars provide strong indications of the clumped nature of their wind. Moreover, we first drew attention to some late-O dwarfs showing extremely weak wind signatures. Consequently, we have derived mass loss rates from STIS spectroscopy that are significantly lower than the current theoretical predictions used in evolutionary models. Because of the limited size of the current sample (and some clear bias toward stars with sharp-lined spectra), these results must however be viewed as tentative. Thanks to the high efficiency of COS in the FUV range, we propose now to obtain high-resolution FUV spectra with COS of a larger sample of SMC O stars to study systematically rotation and wind properties of massive stars at low metallicity. The analysis of the FUV wind lines will be based on our 2D extension of CMFGEN to model axi-symmetric rotating winds. STIS/CCD 11606 Dynamical Hypermassive Black Hole Masses We will use STIS spectra to derive the masses of 5 hypermassive black holes (HMBHs). From the observed scaling relations defined by less massive spheroids, these objects are expected to reside at the nuclei of host galaxies with stellar velocity dispersions greater than 320 km/s. These 5 targets have confirmed regular gas distributions on the scales of the black hole sphere of influence. It is essential that the sphere of influence is resolved for accurate determinations of black hole mass (0.1″). These scales cannot be effectively observed from the ground. Only two HMBHs have had their masses modeled so far; it is impossible to draw any general conclusions about the connections between HMBH mass and their massive host galaxies. With these 5 targets we will determine whether these HMBHs deviate from the scaling relations defined by less massive spheroids. A larger sample will allow us to firmly anchor the high mass end of the correlation between black hole mass and stellar velocity dispersion, and other scaling relations. Therefore we are also conducting a SNAPshot program with which we expect to detect a further 24 HMBH candidates for STIS observation in future cycles. At the completion of this project we will have populated the high mass end of the scaling relations with the sample sizes enjoyed by less massive spheroids. WFC3/ACS/IR 11600 Star Formation, Extinction, and Metallicity at 0.7< z<1.5: H-Alpha Fluxes and Sizes from a Grism Survey of GOODS-N The global star formation rate (SFR) is ~10x higher at z=1 than today. This could be due to drastically elevated SFR in some fraction of galaxies, such as mergers with central bursts, or a higher SFR across the board. Either means that the conditions in z=1 star forming galaxies could be quite different from local objects. The next step beyond measuring the global SFR is to determine the dependence of SFR, obscuration, metallicity, and size of the star-forming region on galaxy mass and redshift. However, SFR indicators at z=1 typically apply local calibrations for UV, [O II] and far-IR, and do not agree with each other on a galaxy-by-galaxy basis. Extinction, metallicity, and dust properties cause uncontrolled offsets in SFR calibrations. The great missing link is Balmer H-alpha, the most sensitive probe of SFR. We propose a slitless WFC3/G141 IR grism survey of GOODS-N, at 2 orbits/pointing. It will detect Ha+[N II] emission from 0.7< z<1.5, to L(Ha) = 1.7 x 10^41 erg/sec at z=1, measuring H-alpha fluxes and sizes for > 600 galaxies, and a small number of higher-redshift emitters. This will produce: an emission-line redshift survey unbiased by magnitude and color selection; star formation rates as a function of galaxy properties, e.g. stellar mass and morphology/mergers measured by ACS; comparisons of SFRs from H-alpha to UV and far-IR indicators; calibrations of line ratios of H-alpha to important nebular lines such as [O II] and H-beta, measuring variations in metallicity and extinction and their effect on SFR estimates; and the first measurement of scale lengths of the H-alpha emitting, star- forming region in a large sample of z~1 sources.
WFC3/ACS/UVIS/IR 11570
Narrowing in on the Hubble Constant and Dark Energy
A measurement of the Hubble constant to a precision of a few percent would be a powerful aid to the investigation of the nature of dark energy and a potent “end-to end” test of the present cosmological model. In Cycle 15 we constructed a new streamlined distance ladder utilizing high- quality type Ia supernova data and observations of Cepheids with HST in the near-IR to minimize the dominant sources of systematic uncertainty in past measurements of the Hubble constant and reduce its total uncertainty to a little under 5%. Here we propose to exploit this new route to reduce the remaining uncertainty by more than 30%, translating into an equal reduction in the uncertainty of the equation of state of dark energy. We propose three sets of observations to reach this goal: a mosaic of NGC 4258 with WFC3 in F160W to triple its sample of long period Cepheids, WFC3/F160W observations of the 6 ideal SN Ia hosts to triple their samples of Cepheids, and observations of NGC 5584 the host of a new SN Ia, SN 2007af, to discover and measure its Cepheids and begin expanding the small set of SN Ia luminosity calibrations. These observations would provide the bulk of a coordinated program aimed at making the measurement of the Hubble constant one of the leading constraints on dark energy.
WFC3/UVI/IR 11557
The Nature of Low-Ionization BAL QSOs
The rare subclass of optically-selected QSOs known as low-ionization broad absorption line (LoBAL) QSOs show signs of high-velocity gas outflows and reddened continua indicative of dust obscuration. Recent studies show that galaxies hosting LoBAL QSOs tend to be ultraluminous infrared systems that are undergoing mergers, and that have dominant young (< 100 Myr) stellar populations. Such studies support the idea that LoBAL QSOs represent a short- lived phase early in the life of QSOs, when powerful AGN-driven winds are blowing away the dust and gas surrounding the QSO. If so, understanding LoBALs would be critical in the study of phenomena regulating black hole and galaxy evolution, such as AGN feedback and the early stages of nuclear accretion. These results, however, come from very small samples that may have serious selection biases. We are therefore taking a more aggressive approach by conducting a systematic multiwavelength study of a volume limited sample of LoBAL QSOs at 0.5 < z < 0.6 drawn from SDSS. We propose to image their host galaxies in two bands using WFC3/UVIS and WFC3/IR to study the morphologies for signs of recent tidal interactions and to map their interaction and star forming histories. We will thus determine whether LoBAL QSOs are truly exclusively found in young merging systems that are likely to be in the early stages of nuclear accretion. WFC3/ACS/IR 11142 Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3< z<2.7 Using HST and Spitzer We aim to determine physical properties of IR luminous galaxies at 0.3< z<2.7 by requesting coordinated HST/NIC2 and MIPS 70um observations of a unique, 24um flux-limited sample with complete Spitzer mid-IR spectroscopy. The 150 sources investigated in this program have S(24um) > 0.8mJy and their mid-IR spectra have already provided the majority targets with spectroscopic redshifts (0.3< z<2.7). The proposed 150~orbits of NIC2 and 66~hours of MIPS 70um will provide the physical measurements of the light distribution at the rest-frame ~8000A and better estimates of the bolometric luminosity. Combining these parameters together with the rich suite of spectral diagnostics from the mid-IR spectra, we will (1) measure how common mergers are among LIRGs and ULIRGs at 0.3< z<2.7, and establish if major mergers are the drivers of z>1 ULIRGs, as in the local Universe, (2) study the co-evolution of star formation and blackhole accretion by investigating the relations between the fraction of starburst/AGN measured from mid-IR spectra vs. HST morphologies, L(bol) and z, and (3) obtain the current best estimates of the far-IR emission, thus L(bol) for this sample, and establish if the relative contribution of mid-to-far IR dust emission is correlated with morphology (resolved vs. unresolved).
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS: (None)
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSAcq 21 21
FGS REAcq 23 23
OBAD with Maneuver 17 17
SIGNIFICANT EVENTS: (None)
